You need to be careful not to hover over a selected object, because then, only the blue connection arrows are displayed.
A connection can be created using one of the small crosses (connection points), or with one of the blue connection arrows. When you hover over a connection point, it will be highlighted green, so you know you are in the right position.
Connections in the library
To insert a connector from the symbol library, click on the connection you want to use., then drag and drop it from the library into position on the drawing area. You can then connect the ends of the connectors to the connection points on any of the objects within your diagram.
Duplicate and connect objects
Click on the blue arrow at the bottom of an object to duplicate it and its content (shape, color, size), and automatically connect the duplicated object to the original. If another object is nearby when you click on the blue arrow, it will not duplicate the object, but instead link the two existing objects together.
By default, a connection with an arrow is used, but you can change this or delete the arrow in the “Style” tab of the format panel.
Tip: There are several ways to duplicate shapes and work with connectors.